Remote control system



Nov. 27, 1945.

T. W. HAYS REMOTE CONTROL SYSTEM Filed Oct. 8, 1943 ff?? i lili/J7 ATTORNEY Patented Nov. 27, 1945 REMOTE CONTROL SYSTEM Thomas W. Hays, Salt Lake City, Utah, assignor to The Union Switch and Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application October 8, 1943, Serial No. 505,504 (Cl. 246-3) 2 Claims.

My invention relates to remote control systems, andmore particularly, to centralized traflic control systems for railroads in which the condition of a plurality of devices located at spaced points along a stretch of railroad track is indicated at a central oilice by the transmission of impulse codes.

In systems of this character it may happen that a temporary change in the condition of a movable device, the condition of which it is desired to record at the office, occurs at a time when the line circuit over Which the codes are transmitted is in use, and that the device is restored to normal before the line circuit becomes available for the'transmission 'of an indication oi its changed condition.

The object of my invention is to prevent the loss of a record of the change in condition under these circumstances, by storing it at the eld station until the line circuit becomes available, and for there effecting the transmission of two successive codes, the rst indicating the changed condition of the device, and the second indicating the normal condition in which it stands at the time of transmission.

My invention is of particular utility in connection with the transmission of OS indications of the movement of trains over a stretch of railroad track.

Referring to the accompanying drawing, the track diagram shown therein includes a relatively short track section IT provided with a closed track circuit including a source of current IB and a track relay I TR, which section, it is to be understood, is one of a number of OS sections located at spaced points in a stretch of single track railway, from which reports of train`movements are desired, section IT as shown being the usual detector section for a track switch IW forming one end of a passing siding. It is also to be understood that a suitable communication system is provided, having a coding unit at each such location for transmitting impulse code indications of the condition of movable devices to a central oiice over an intermittently available line circuit, not shown, the movable devices including track relays such as the track relay ITR by means of which the movement of trains is visually indicated at a central oiice by the lighting of lamps in a miniature track diagram and recorded on a chart by the operation of a suitable graphic recorder.

The communication system may be of any suitable type, but as shown, it is assumed to be one employing a normally energized starting relay such as the relay S, for the initiation of indication codes in response to a change in condition of any one of a group of movable devices to be indicated. Suitable systems are shown, for example, in the Letters Patent of the United States No. 2,292,245, issued August 4, 1942, to C. S. Snavely et al., for Remote control systems,

Vand in the pending application for Letters Patent of the United States Serial No. 496,907, filed July 31, 1943 for remote control systems, by A. 1:'` Jackel.

My invention is an improvement upon that shown in Fig. 5B of the above-mentioned Snavely et al. patent, and isshown herein as employingthe code system of that patent for the transmission of indications of the condition of the track relay ITR. More particularly, it is to be understood that the apparatus Within the rectangle designated Coding um't corresponds with that of the station apparatus of Figs. 2A, 2B and 2C of United States Patent No. 2,292,245, and that its operation for the transmission of indications of the condition of the track section IT is governedby a storing relay ITKS and a slow release relay Z interposed between the track relay I TR and the coding unit, and arranged in accordance with my invention.

The operation of the apparatus of my invention will now be described, and the novel features thereof Will then be pointed out in claims.

Normally, relays I TKS and Z are both deenergized. If a train enters section IT, relay ITR releases to complete a circuit from one terminal B of a suitable local source of current through the winding of relay ITKS and over the back contact a of relay I TR to the other terminal C of the same source. Relay ITKS therefore picks up, its contact b interrupting the normally closed stick circuit for the starting relay S extending from terminal B at its front contact a through its winding and over contact b of relay ITKS, and thence to terminal C over a circuit IGI which may include other similar contacts as shown in the above-mentioned United States Patent No. 2,292,245. Relay S releases quickly and the opening of its contact d disconnects ter.. minal B at back contact a of the coding unit relay IGP, from relay Z, so that relay Z remains released. The closing of back contact c of relai7 S completes a starting circuit such as circuit III! of the Snavely et al. patent, and assuming the code line to be free and relay I TR to remain released, a code will be initiated which includes an element controlled over circuit |23 of the Snavely et al. patent and front contact c of relay ITKS to indicate that fact. At the end of the code, relay I4P is operated momentarily, the closing of its front contact a resulting in the reenergization of relay S, and the subsequent closing of its back contact a completing a circuit from terminal B over front Contact d of relay S and front contact a of relay ITKS to pick up relay Z. When relay I'IKS picked up, it completed its stick circuit extending from terminal B through its winding to terminal C over contacts a of relays Z and ITKS, which circuit is opened when relay Z picks up.

If relay ITR picks up after the track occupied code has been transmitted, relay ITKS releases, thereby releasing relay S to initiate a second code which will include an element controlled over circuit I2'I, to indicate that section IT is unoccupied.

Assuming now that a short high speed train passes through section IT when the code system is in use, so that relay ITR. releases to pick up relay ITKS and release relay S, and then picks up again before the track occupied code is transmitted, it will be seen that relay S will remain released to store the starting condition until the line becomes free, relay ITKS being held energized over its stick circuit to store the track occupied indication after .relay I'I'RI picks up. The momentary energization of relay I4P at the end of the code during which the track occupied condition is indicated results in the sequential operation of relays S and Z, as before, but in this instance relay Z releases relay I'IKS by opening its stick circuit. Consequently relay S releases again, due to the release of relay II'KS, to initiate a second code during which circuit |21 is energized toY indicate the track clear condition, as required.

It may happen that relay I'I'R. releases during the transmission of a code containing a track clear element, that is to say, after the transmission of a track clear element in a code ,initiated bythe release of Yrelay S, but before relay S becomes reenergized. `As .explained in the Snavely et al. patent, another relay M is energized over circuit IUI during the transmission of the indicating elements of anode. Relay `M will release when relay ITKS picks up in response to the release of relay ITR. under the condition referred to, to interrupt the code without operating relay MP, and the code will then be retransmitted to include the track occupied element ycorresponding to the energized position of Yrelay ITKS, thereby insuring the correct transmission of the indications regardless of when relay ITR changes its position.

In the system of the Jackel application above referred to a similar result is .attained in a different manner. In this system the starting relay corresponding 'to relay S is reenergized prior to the transmission of the indicating elements and is held energized over a circuit similar to circuit IOI during the transmission of these elements,

and consequently will be released by relay ITKS if Vrelay ITRreleases during the transmission of these elements, and in condition to initiate a new code including the track occupied element as required. In either system, it is to be understood that relay Z is to be arranged to be energized momentarily at the end of a code only if relays S and ITKS are both picked up, so that its energization indicates the transmission of a complete code including a track occupied element as described.

Although I have herein shown and described only one form of remote control apparatus embodying my invention, it is understood that various changes and modications may be madey therein within the scope of the appended claims" without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In a remote control system, a coding unit for transmitting impulse codes for indicating the condition of a movable device, a stick relay having a pick-up circuit including a contact closed in one position of said movable device, a normally energized .starting relay effective when released to initiate the operation of said coding unit, a holding circuit for the starting relay including contacts which open the circuit momentarily in response to a change in position of said stick relay, a pick-up circuit for the starting relay closed during the operation of said coding unit, a slow release relay, an energizing circuit for said slow release relay includingfront contacts of the starting relay and of the stick relay, anda contact controlled by the coding unit which closes at the end of a complete code; a circuit for holding said stick relay energized independently of the condition of said movable device including its own front contact and a back contact of said slow release relay, and an indication circuit for controlling said coding unit controlled in accordance with the position of said stick relay.

2. In a centralized ,traic control system for railroads, a detector track section, a normally closed track circuit for said section including a track relay, a storing relay controlled vby aback contact of said track relay, a normally deenergized relay, a stick circuit 4for holding said storing relay energized when said track ,relay .is picked up including a back contact of said normally deenergized relay, a coding unit for transmitting impulse codes for indicating the condition of said storing relay, a starting relay vhaving ,a normally closed stick circuit, means for opening the stick circuit for said starting relay whenever a change occurs in the condition of Vsaid storing relay, means for initiating the operation of `said coding unit in response to the release of said starting relay, to transmit a code indicating the condition of said storing relay, means for reenergizing the starting relay during the transmission of .such code, and a circuit for said vnormally deenergized relay including a contact closed when the coding unit is in its normal at rest condition and also including front contacts of said starting relay and of said storing relay.

THOMAS W. HAYS. 

